1. Field of the Invention
This invention relates to a method and an apparatus for the printing of languages which use the Arabic-Farsi script.
2. Description of the Prior Art
In languages which use the Arabic-Farsi script, the alphabetic characters have a phonetic similarity with the English alphabet, but each character assumes different shapes depending on its location in a word and on the character or symbol that precedes and follows it.
The multiplicity of shapes helps in information compression, as characters need not be written in their complete and isolated form. This advantage in the handwritten form, however, has led to problems in printing and reading this family of languages.
The complexity of transfer from the handwritten word to print may be considered and solved at five levels of decreasing difficulty and cultural acceptance:
I. Handwritten reproduction, using the precision and elegance of calligraphy, with the diacritics to indicate phonetic emphasis clearly indicated. This method has been used historically for the printing of literature and holy scriptures.
II. A simplified version of calligraphy used for everyday writing. This script is usually written without diacritics and may be slightly different in appearance among Urdu, Farsi and Arabic.
III. A simplified subset of the script adapted for manual or electric typewriters. These, depending on their design, are likely to have four shapes and keys for each character, i.e. initial, final, medial and isolated; in some cases only two, initial (also used as medial) and final (also used as isolated). The user supplies the linking information, shifting the carriage on the typewriter keyboard in the middle of the word if necessary, depending on the position of the character in the word. The typing process, because of this added requirement to remember the context, is relatively slow.
IV. The next level of simplification is to have only one form per character. This printed form is quite different from the handwritten script. In communication systems that use Teletype or similar output devices, this involves minimum technical modification. By using a modified printing head, and reversing the direction of printing, an English Teletype can be used to print Arabic-like languages. Since the output has little resemblance to the written form, user acceptance would require a radical break with deepseated cultural tradition.
V. Yet another level of simplification is the replacement of the Arabic script characters by a phonetically equivalent English alphabet. The language is altered to be written in Roman form, and is phonetically and semantically the same as before. Visually it is radically different. This involves no technical modification to the printing device. It is apparent that at present functional efficiency in printing and aesthetic quality are at opposite ends of the scale. Furthermore, the choice of a particular method of printing is determined by such diverse factors as effect on employment, cultural tradition, requirement for high speed output, cost, appearance, equipment reliability and availability, and resistance to change.
At present the language is transcribed to the printed form either by hand (level I) or by mechanical means (level III), both of which are very slow methods compared to the printing speed of western languages.
For telecommunications, solutions at level IV using isolated characters have been implemented on telextype equipment on an experimental basis. As stated earlier this is an unsuitable solution, since the machine output has little resemblance to the written form.
It has been stated earlier that in the languages using Arabic-Farsi script the shape of a character is dependent upon its location and contextual position in a word. Consequently printing devices must have multiple keys and shapes for a single character of the alphabet. A user must, on the basis of his knowledge of the script, make the right choice of character shape. This makes the process of transcribing the language slow and tedious, while, at the same time, the devices used are themselves cumbersome and inefficient.